A rebel soldier who cut out and ate the heart of a dead government soldier has posted the video online in a development that shows the extent to which the situation in Syria has degenerated.

“The unverified clip, posted by a pro-government campaign group, claims to show a man – believed to be Abu Sakkar, the well-known founder of Homs’ Farouq Brigade – standing over the uniformed corpse in a ditch while ranting against President Bashar al Assad,” says a report in UK’s Daily Mail.

“Using a knife, the man hacks open the torso and removes two organs before holding them up to the camera and declaring: ‘I swear to God we will eat your hearts and your livers, you soldiers of Bashar the dog.’ He then raises one to his mouth and takes a bite,” according to the report.

The man’s rant is unbelievably greeted by offscreen cheers of his comrades shouting “Allahu akbar (God is great).”

Human rights groups say the video, posted on YouTube by and billed as proof of a war crime, is emblematic of a civil war that has rapidly descended into sectarian hatred and revenge killings.

Peter Bouckaert of Human Rights Watch said that he had seen an original, unedited copy of the video and that Abu Sakkar's identity had been confirmed by rebel sources in Homs and by images of him in other videos wearing the same black jacket as in the latest clip and with the same rings on his fingers.

“The mutilation of the bodies of enemies is a war crime. But the even more serious issue is the very rapid descent into sectarian rhetoric and violence,” Bouckaert was quoted as saying.

He said that in the unedited version of the film, Abu Sakkar instructs his men to “slaughter the Alawites and take their hearts out to eat them,” before biting into the heart.

Abu Sakkar has been seen in previous videos firing rockets at Lebanese Shi’ite villages on the border and posing with the body of a soldier purportedly from the Lebanese Shi’ite militant Hezbollah group, which is helping Assad’s forces.

Last month, a photograph was released by a pro-Assad group based in Lebanon that appeared to show a young rebel fighter barbecuing the severed head of a government soldier.

The Syrian conflict started with peaceful protests in March 2011, but when these were suppressed it gradually turned into an increasingly sectarian civil war which, according to one opposition monitoring group, has cost more than 80,000 lives.

Majority Sunni Muslims lead the revolt, while Assad – whose family have ruled for over four decades – gets his core support from his own Alawite sect, an offshoot of Shi’ite Islam.